<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <title></title>
    <style>
        #box {
            width: 200px;
            height: 200px;
            background-color: red;
        }

        .show {
            display: block;
        }

        .hide {
            display: none;
        }
    </style>
</head>

<body>
    <input type="button" value="隐藏" id="btn" />

    <div id="box"></div>
    <script>

    </script>
</body>

</html>